Physical Unclonable Functions in Integrated Circuit Chip Packaging for Security

ABSTRACT

In the invention described, magnetic field characteristics of randomly placed magnetized particles are exploited by using the magnetic field fluctuations produced by the particles as measured by a sensor. The magnetized particles generate a complex magnetic field near the surface of an integrated circuit chip that can be used as a “fingerprint.” The positioning and orientation of the magnetized particles is an uncontrolled process, and thus the interaction between the sensor and the particles is complex. The randomness of the magnetic field magnitude and direction near the surface of the material containing the magnetic particles can be used to obtain a unique identifier for an item such as an integrated circuit chip carrying the PUF.

CROSS REFERENCES TO RELATED APPLICATIONS

None.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates generally to anti-counterfeit systems andmore particularly to physical unclonable functions.

2. Description of the Related Art

Counterfeit integrated circuit chips (“ICCs”) are a major concern in theelectronic component supply industry because of reliability and securityissues. Such counterfeit ICCs are impacting many industrial sectors,including computers, printing, telecommunications, automotiveelectronics, medical, banking, energy/smart-grid, aerospace, andmilitary systems. The consequences can be dramatic when critical systemsbegin to fail or act maliciously due to the use of counterfeit orlow-quality components causing minor, major, or mission failures,including health or safety concerns.

The National Defense Authorization Act (NDAA) of 2012, for example, isfocused on defense contractors who do not screen their equipment forcounterfeit parts. There can be civil and criminal liability forcontractors who do not eliminate counterfeit electronic parts inmilitary equipment, according to the Forbes article, “NDAA May PutDefense Contractors In Prison For Counterfeit Parts,” Feb. 14, 2012.

The tools and technologies utilized by counterfeiters have becomeextremely sophisticated and well financed. In turn, this also calls formore sophisticated methods to detect counterfeit electronic parts thatenter the market. Hardware intrinsic security is a mechanism that canprovide security based on inherent properties of an electronic device. Aphysical unclonable function (“PUF”) belongs to the realm of hardwareintrinsic security.

In the printer industry, counterfeit printer supplies including ICCs area problem for consumers. Counterfeit supplies may perform poorly and maydamage printers. Printer manufacturers use authentication systems todeter counterfeiters. PUFs are a type of authentication system thatimplements a physical one-way function. Ideally, a PUF cannot beidentically replicated and thus is difficult to counterfeit.Incorporating a PUF in electronic device packaging, including ICCs,deters counterfeiters.

SUMMARY

In the invention described, magnetic field characteristics of randomlyplaced magnetized particles are exploited by using the magnetic fieldfluctuations produced by the particles as measured by a sensor, such asa Hall-effect sensor, or an array of such sensors. The inventionconsists of an ICC encased in or over-molded by a substrate thatcontains magnetic particles. The magnetized particles generate a complexmagnetic field near the surface of the ICC that can be used as a“fingerprint.” The positioning and orientation of the magnetizedparticles is an uncontrolled process, and thus the interaction betweenthe sensor and the particles is complex. Thus, it is difficult toduplicate the device such that the same magnetic pattern and particlephysical location pattern will arise. The randomness of the magneticfield magnitude and direction near the surface of the materialcontaining the magnetic particles can be used to obtain a uniqueidentifier for an item such as an integrated circuit chip carrying thePUF. Further, the placement of the device in the top layer of anintegrated circuit chip protects the underlying circuits from beinginspected by an attacker, e.g., for reverse engineering. When acounterfeiter attempts to remove all or a portion of the coating, themagnetic field distribution must change, thus destroying the originalunique identifier.

The invention, in one form thereof, is directed to an integrated circuitchip overlain or encapsulated by a PUF comprising randomly placedmagnetic particles.

The invention, in another form thereof, is directed to an integratedcircuit chip used in a printer or printer supply component, such as atoner cartridge, that is overlain or encapsulated by a PUF comprisingrandomly placed magnetic particles.

The invention, in yet another form thereof, is directed to an EMV(Europay, Mastercard, Visa) transaction chip or embedded microchip on abank card overlain by a PUF comprising randomly placed magneticparticles.

The invention, in yet another form thereof, is directed to an apparatushaving an EMV transaction chip mounted on substrate that forms the bodyof a bank card, where a plurality of magnetized particles are dispersedin the substrate to form a PUF.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification, illustrate several aspects of the present disclosure, andtogether with the description serve to explain the principles of thepresent disclosure.

FIG. 1 is a view of an integrated chip.

FIG. 2 is a view of an integrated chip with magnetized particles moldedinto the housing.

FIG. 3 is a view of an integrated chip with an array of sensors formedabove the chip with magnetized particles molded into the housing.

FIG. 4 is an orthogonal view of a substrate containing magnetic andnon-magnetic particles.

FIG. 5 is a side view of a PUF and PUF readers.

FIG. 6 is a view of the front of a bank card with an EMV transactionchip.

FIG. 7 is a view of the back of a bank card with a magnetic strip.

FIG. 8 is a bank card chip reader device.

FIG. 9 is an end view of the bank card chip reader device.

FIG. 10 is a flowchart of a method of making a secure device.

FIG. 11 is a magnetic field profile along a defined path.

FIGS. 12a, 12b, and 12c are three-dimensional representations of themagnetic flux density measured across the area resolved into threecoordinate components, B_(x), B_(y), and B_(z).

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings where like numerals represent like elements. The embodimentsare described in sufficient detail to enable those skilled in the art topractice the present disclosure. It is to be understood that otherembodiments may be utilized and that process, electrical, and mechanicalchanges, etc., may be made without departing from the scope of thepresent disclosure. Examples merely typify possible variations. Portionsand features of some embodiments may be included in or substituted forthose of others. The following description, therefore, is not to betaken in a limiting sense and the scope of the present disclosure isdefined only by the appended claims and their equivalents.

Referring now to the drawings and particularly to FIG. 1, when an ICC1001 is manufactured, it is typically packaged by being attached to ametal lead frame 1008 that is connected to solder pads 1002 and 1003 bya wire bonds 1004 and 1005, and then enclosed in an encapsulant 1006which is then cured. The encapsulated chip is then molded into a plastichousing 1007.

Referring now to FIG. 2, in one embodiment of the invention, the moldedplastic housing 1007 is replaced with the molded plastic housing orsubstrate 2007 where dispersed in the substrate is a plurality ofmagnetized particles 4014. The particles are distributed randomly suchthat it is extremely difficult to reproduce the exact distribution andalignment of particles. Preferably, the particles are magnetized beforedispersion in the substrate to add further randomness to the resultingmagnetic field profile. Thus, the substrate 2007 and the particles 4014form a physical unclonable function out of the molded plastic housing.

The magnetic field profile near the surface of the ICC may be measuredby an external magneto-resistive sensor (not shown), a Hall-effectsensor (not shown), or an array of such sensors, in close proximity tothe top surface of the ICC. Since the sensing elements are typicallyaround 0.3-0.5 mm below the surface of the sensing device, the averageparticle size diameter using Hall-effect sensor or magneto-resistivesensor is preferably greater than 0.1 mm. Note that the diameter of anon-spherical particle is the diameter of the smallest sphere thatencloses the particle. Other sensor options include magneto-opticalsensor technology, which is capable of working with smaller magneticparticle sizes, but is more costly to implement and subject tocontamination problems.

The magnetic field profile measurements may be taken within a definedarea or along a defined path: straight, circular, or any arbitrarilyselected and defined path, and recorded at the ICC foundry. FIG. 11shows a magnetic field profile along a defined path where the magneticflux density has been resolved into three coordinate components B_(x),B_(y), and B_(z). FIG. 12 shows a magnetic field profile measured over arectangular area as would be exhibited by the defined area overlaying anICC. The profile is a three-dimensional representation of the magneticflux density measured across the area. The magnetic flux density vectorhas been resolved into three coordinate components, B_(x), B_(y), andB_(z), shown separately in FIGS. 12a, 12b, and 12c . The magnetic fieldprofile data would be signed by a private key and written to the ICC'snon-volatile memory (“NVM”) during programming. After installation ofthe ICC onto a circuit card, the magnetic “fingerprint” is once againread by an external magneto-resistive sensor and the magnetic profile iscompared to the values stored on the chip to authenticate the ICC. Thissystem would make it very difficult for counterfeit ICCs to make theirway into high value applications. The system would be fairly inexpensiveto implement with almost instantaneous authentication of the PUFover-molded ICCs.

Referring now to FIG. 3, in a second embodiment of the invention, theuse of magnetized particles 4014 creates a unique magnetic fingerprintthat can be applied to the manufacture of ICCs by over-molding theencapsulated chip 1001 with a substrate containing magnetized particles2007. The term “over-molded” is used here broadly to mean anything fromadding a partial surface layer over the ICC to completely encasing theICC. One or more sensors, such as a Hall-effect sensor 3001 is formedabove the chip body and encased within the housing 2007. In thisembodiment, the sensor(s) 3001 can record a series of analog magneticintensity readings, in various locations along the substrate, in one,two, or three coordinate directions. Such an “internal” Hall-effectsensor can measure average particle size diameters that are less than0.1 mm. Since these measurements are analog voltages, with a sufficientnumber of measurements and sufficient analog to digital resolution,unique values can be derived from the measurements. These values can beused for private keys, seeds, etc. which are not stored in the device'smemory. Instead, they are read and derived by the device “in flight”(i.e., during operation), thus rendering ineffective any probing attacksby counterfeiters on the chip itself. If a counterfeiter were to attemptto extract the private key from the ICC, it is highly probable that theover-molded magnetic layer will be disturbed and the private key wouldbe lost.

These embodiments may, for example, be implemented on an integratedcircuit chip on a printer or printer supply component, such as a tonercartridge, that is used to authenticate the toner cartridge for whateverpurpose, as well as to perform other functions such as toner levelmonitoring, sheet count, etc.

A third embodiment of the invention is the application of the PUFauthentication technology to bank cards and identification cards with anEMV transaction chip. Bank cards 6001, for example, are under constantattack by counterfeiters. For this reason an EMV transaction chip 6002mounted on a substrate 6003 that replaced the easily counterfeitedmagnetic strip 7001 shown in FIG. 7, the back of the bank card 6001. Toavoid fraud, the EMV transaction chip may be used with a personalidentification number (“PIN”), but many cards lack this extra protectionfor convenience of the customer, to reduce data requirements intransactions, and to avoid software upgrades for the PIN operation.

Bank cards with EMV transaction chips are mostly used in a contact-basedform: the card is inserted into a reader, which creates a circuit thatallows handshaking between the card and the payment terminal. A uniquetransaction is created that involves cryptographic data embedded in thechip.

For cards that require PINS, the transaction can't be completed withoutthe code, which is not transmitted remotely as with debit and ATMtransactions. Some cards are equipped with near-field communications(NFC) radios for contactless EMV transaction, and will work withpoint-of-sale systems.

A unique magnetic PUF signature of the analog magnetic intensityreadings could replace the PIN requirement to authenticate the bankcard. The PUF signature would be a second factor authentication for thebank card.

The substrate of a bank card may be fabricated where dispersed in thesubstrate is a plurality of magnetic particles. The particles aredistributed randomly such that it is extremely difficult to reproducethe exact distribution and alignment of particles. Thus, the substrateand the particles of the bank card form a physical unclonable function.The magnetic field profile may be measured by an external sensor, suchas a Hall-effect sensor (not shown) in close proximity to the bank cardsurface. Other sensor options include magneto-optical sensor technology.The magnetic field profile measurements may be taken within a definedarea or along a defined path: straight, circular, or any arbitrarilyselected and defined path, and recorded during manufacture of the bankcard. The magnetic field profile data would be written to the EVMtransaction chip's non-volatile memory.

When inserted into a card reader 8001, the reader could sweep a sensorarm across a portion of the bank card and one or more sensors, such asHall-effect sensors, located on the sensor arm would measure themagnetic field in a defined area or along the defined path. A simplemechanical configuration with a drive cam would determine the path ofthe sensor arm sweep. Alternatively, as shown in FIG. 9, the sensor orsensor array could be at a fixed location where the bank card slidesacross the sensors 8003, 8004, 8005, and 8006 as the bank card isinserted into the reader slot 8002. Data corresponding to the magneticintensity readings along the sensing path stored in the EMV transactionchip's non-volatile memory and used to validate the magnetic“fingerprint” detected by the card reader at time of the transaction.This invention does not require the user to remember a PIN, and the cardreader can perform the validation locally. Alternatively, the cardreader could be configured to transmit the magnetic “fingerprint” to thebank card company server or cloud location for remote authenticationwhen high value transactions are taking place. Data that is stored in acloud location is stored in an accessible network such as the Interneton physical storage devices such as computer servers and storagenetworks.

As an added layer of security, the EMV transaction chip on the cardcould contain information that would guide the card reader to read themagnetic “fingerprint” in a specific location on the bank card. Thislocation could be different for different cards and would add yetanother layer of complexity to the task of counterfeiting a bank card. Avarying position of the magnetic “fingerprint” could also be configuredto act as a rotating encryption key. This rotating key could change on adaily, weekly, or monthly basis. The rotating key could be as simple astwo keys in which data is read off the “fingerprint” in a forward orreverse motion, which would be the least disruptive to current cardreader configurations. Known algorithms could be utilized to determinewhen the “fingerprint” rotates.

In another embodiment, the bank card substrate to which the EMVtransaction chip is mounted could be the location of a magnetic“fingerprint” such that removal or alteration of the EMV transactionchip would distort the substrate and thus alter the magnetic“fingerprint,” rendering the authentication inoperable. In a furtherembodiment, the bank card could be implemented in such a way as to causetearing to the fingerprint if the chip is removed.

The card reader may initiate the bank card authentication by sending arequest to the EMV transaction chip on the bank card for data. The bankcard EMV transaction chip may challenge the card reader and wait for aproper response (authenticating the reader) before the bank cardsecurity chip transmits the magnetic “fingerprint” authentication datato the reader. This challenge and response protocol makes it moredifficult for counterfeiters to acquire data from the bank card. Inaddition to using the magnetic “fingerprint” or signature of the bankcard, capacitive sensing technology may be used to detect the presenceof the randomly distributed magnetized particles in the bank card, whichcould provide yet another authentication step for validating the bankcard.

If at least one face of the bank card is non-opaque, the presence of themagnetized particles could be detected optically by a digital camerachip or by an optical sensor. Similar to capacitive sensing, this couldprovide an additional authentication step for the bank card.

This technology could also be used in the same manner described above toauthenticate access badges for secure facilities, or for otherapplications such as passports, government identification cards, driverlicenses, etc. The PUF technology could stand alone as a securitydevice, or in combination with a integrated circuit chip on theidentification card or other security device having non-volatile memory.

FIG. 4 shows a region of a substrate 4010. Dispersed in the substrate isa plurality of magnetized particles 4014. The particles are distributedrandomly such that it is extremely difficult to reproduce the exactdistribution and alignment of particles. Thus, the substrate 4010 andthe particles 4014 form a PUF.

FIG. 5 shows a side view of the substrate 4010 containing the magnetizedparticles 4014.

The field data may be measured while moving the PUF relative to astationary magnetic field sensor(s) 5001, 5002, 5003 or by moving themagnetic field sensor(s) 5001, 5002, 5003 next to a stationary PUF, etc.The sensors are shown in varying orientations, but such a variedorientation is not necessary. Multiple sensors may be used to reduce themovement and time required to measure the magnetic field over a desiredarea.

FIG. 10 shows an example of a method of making a secure device, such asan integrated circuit chip with a PUF overlay or a bank card with an EMVtransaction chip with a PUF substrate.

The magnetizable particles may be of any shape, and may containneodymium and iron and boron. Alternatively, the magnetizable particlesmay contain samarium and cobalt. Preferably, the magnetized particlesgenerate a sufficiently strong magnetic field to be detected with alow-cost detector.

Suitable substrate materials are used that allow formed aggregatepellets of the substrate material and particles to be magnetized. Themagnetizable particles are magnetized by, for example, subjecting thepellets to a strong magnetic field. After magnetization, the magneticparticles do not clump together because the pellet carrier material is asolid. During the molding process, the pellets are heated and meltedprior to molding.

The substrate carrier is then solidified in an ICC, overlaying an ICC,encasing an ICC, in the body of a bank card, or in the section of a bankcard beneath the section of a bank card beneath the position of an EVMtransaction chip. In an alternate embodiment the carrier may be, forexample, a liquid that is caused to become solid by adding a chemical,subjecting to ultraviolet light, increasing its temperature, etc.Causing the carrier to become solid locks the distribution andorientation of the particles. In this case a high viscosity liquid ispreferred so that the particles may be magnetized shortly before thematerial is molded. The high viscosity retards the movement of themagnetic particles toward each other while the material is in a liquidstate and minimizes clumping of the magnetized particles. Clumping couldcause failures of the over-molding process.

Magnetizing the particles in pellet form yields a more random magneticfield pattern, and is therefore more difficult to clone. Further, theapplication of a magnetizing field with patterned or randomizedorientation may be applied to a formed substrate with random particlepositions in order to cause greater diversity of magnetic fieldorientation.

The foregoing description illustrates various aspects and examples ofthe present disclosure. It is not intended to be exhaustive. Rather, itis chosen to illustrate the principles of the present disclosure and itspractical application to enable one of ordinary skill in the art toutilize the present disclosure, including its various modifications thatnaturally follow. All modifications and variations are contemplatedwithin the scope of the present disclosure as determined by the appendedclaims. Relatively apparent modifications include combining one or morefeatures of various embodiments with features of other embodiments.

What is claimed is:
 1. An apparatus comprising: a substrate; a pluralityof pre-magnetized particles that have random orientations ofmagnetization and are randomly dispersed in the substrate; and anintegrated circuit chip, wherein the substrate containing the pluralityof pre-magnetized particles is formed into a housing that encapsulatesthe integrated circuit chip.
 2. The apparatus of claim 1, furthercomprising a non-volatile memory on the integrated circuit chip, whereinthe non-volatile memory contains magnetic field profile data measuredfrom the pre-magnetized particles.
 3. The apparatus of claim 1, whereinthe pre-magnetized particles contain neodymium and iron and boron. 4.The apparatus of claim 1, wherein the pre-magnetized particles containsamarium and cobalt.
 5. The apparatus of claim 1, wherein the averageparticle size diameter of the pre-magnetized particles is greater than0.1 mm.
 6. The apparatus of claim 1, wherein the average particle sizediameter of the pre-magnetized particles is greater than 0.001 mm.
 7. Anapparatus comprising: a substrate; a plurality of pre-magnetizedparticles that have random orientations of magnetization and arerandomly dispersed in the substrate; an integrated circuit chip; and atleast one sensor positioned in contact with the integrated circuit chip,wherein the substrate containing the plurality of pre-magnetizedparticles is formed into a housing that encapsulates the integratedcircuit chip and the at least one sensor.
 8. The apparatus of claim 7,further comprising a non-volatile memory on the integrated circuit chip,wherein the non-volatile memory contains magnetic field profile datameasured from the pre-magnetized particles.
 9. The apparatus of claim 7,wherein the pre-magnetized particles contain neodymium and iron andboron.
 10. The apparatus of claim 7, wherein the pre-magnetizedparticles contain samarium and cobalt.
 11. The apparatus of claim 7,wherein the average particle size diameter of the pre-magnetizedparticles is greater than 0.1 mm.
 12. The apparatus of claim 7, whereinthe average particle size diameter of the pre-magnetized particles isless than 0.1 mm.
 13. An apparatus comprising: a substrate; a pluralityof pre-magnetized particles that have random orientations ofmagnetization and are randomly dispersed in the substrate; an integratedcircuit chip; and a non-volatile memory on the integrated circuit chip,wherein the integrated circuit chip is over-molded with the substratecontaining the pre-magnetized particles, and the non-volatile memorycontains magnetic field profile data measured from the pre-magnetizedparticles.
 14. The apparatus of claim 13, wherein the pre-magnetizedparticles contain neodymium and iron and boron.
 15. The apparatus ofclaim 13, wherein the pre-magnetized particles contain samarium andcobalt.
 16. The apparatus of claim 13, wherein the average particle sizediameter of the pre-magnetized particles is greater than 0.1 mm.
 17. Theapparatus of claim 13, wherein the average particle size diameter of thepre-magnetized particles is less than 0.1 mm.
 18. The apparatus of claim13, wherein the integrated circuit chip is used in a printer or printersupply component, such as a toner cartridge.